Detection of Schmallenberg virus in bull semen

[Gert van der Hoek]

Date: Wed 19 Dec 2012

From: Martin Beer Martin.Beer@fli.bund.de [edited]


Detection of Schmallenberg virus RNA in semen samples
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In the framework of a study co-financed by the European Union, the Friedrich-Loeffler-Institut (FLI) analyzed the semen of bulls with a known SBV-antibody status for the presence of Schmallenberg virus (SBV) genome. All samples were investigated with an optimized RNA extraction method and a real-time RT-PCR (RT-qPCR) system developed and established at the FLI.

At present, 740 semen batches from 94 SBV-infected and seroconverting/seroconverted bulls have been analyzed. 26 semen batches from 11 bulls reacted positive in the RT-qPCR analyses with Cq-values from 26 to 37. In 3 of the 11 bulls with SBV-genome positive semen samples, also 1st SBV-antibodies could be detected. In 2 bulls SBV-genome could be detected for more than 40 days in 6 or 8 consecutive semen batches, respectively. Furthermore, in one bull a pattern of PCR-positive and PCR-negative consecutive semen batches was observed within 43 days (5 batches positive / 2 batches negative / 2 batches positive / 2 batches negative / 1 batch positive). This points to intermitting virus excretion in semen. However, it is currently unclear and topic of further studies, how long after seroconversion this situation may persist.

In addition, in vitro and in vivo studies about the infectivity of the SBV-positive semen samples are ongoing.

ProMED-mail

[Gert van der Hoek]

Re: Detection of Schmallenberg virus in bull semen

Date: Thu 20 Dec 2012

From: Wim van der Poel [edited]

wim.vanderpoel@wur.nl


Detection of Schmallenberg virus RNA in semen samples
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The Central Veterinary Institute (CVI) of Wageningen University and Research Centre in Lelystad, the Netherlands, and the French Agency for Food and Environmental and Occupational Health and Safety (ANSES) can confirm from their own observations the detection of Schmallenberg virus [SBV] RNA in semen samples, as reported by the Friedrich-Loeffler-Institut on 19 Dec 2012.

At CVI, 55 semen samples produced in 2012 by 8 seroconverting/viraemic bulls have been analysed using a real-time RT-PCR system developed by FLI and an RNA extraction method developed by CVI. In total, 3 samples produced by 2 different bulls tested positive.

At LNCR (National Laboratory for sanitary controls in breeding animals, France) together with ANSES, 904 semen samples produced in 2011 and 2012 by 160 seropositive bulls have been analysed using a real-time RT-PCR system developed by FLI and an RNA extraction method developed by LNCR. In total 26 samples produced by 2 different bulls were tested positive for 2 to 3 months.

Because of these findings, the institutes are currently performing in vitro and in vivo studies on SBV excretion in semen. These studies are supported by the European Union and the national governments.

In the meantime, to declare semen free of SBV, it is advised to test semen samples for the presence of SBV RNA using an approved RT-PCR and RNA extraction method, unless the semen was produced before 31 May 2011 or the bull was tested SBV antibody negative at least 28 days after production.


Prof Dr Wim H M van der Poel (Department of Virology)

Dr Ruth Bouwstra, Dr Johan Bongers (Department of Diagnostics)

Central Veterinary Institute of Wageningen University and Research Centre, Lelystad, the Netherlands.

Dr Stephan Zientara, French Agency for Food and Environmental and Occupational Health and Safety;

Dr Claire Ponsart, National Laboratory for sanitary controls in breeding animals, France.

More: ProMED-mail

[Gert van der Hoek]

Re: Detection of Schmallenberg virus in bull semen

SCHMALLENBERG VIRUS - EUROPE (07): (GERMANY) VIRUS RNA IN BOVINE SEMEN
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Date: Wed 23 Jan 2013

From: Martin Beer Martin.Beer@fli.bund.de [edited]


Recently, the Friedrich-Loeffler-Institut (FLI) reported about the detection of Schmallenberg virus (SBV)-genome in semen. In 26 semen batches from 11 bulls, SBV-genome could be detected by real-time RT-PCR.

For verification of the infectious status of SBV-positive semen batches, 6 calves were experimentally inoculated in a 1st study. Each animal received pooled semen of 5 straws from one semen batch subcutaneously. The selected semen batches originated from 6 different bulls and represented batches with variable SBV-genome loads. Following inoculation, no clinical symptoms were seen in the animals.

However, for 2 of the 6 calves, an SBV infection could be confirmed by both real-time RT-PCR and subsequent SBV-seroconversion. In 4 of the 6 calves, neither SBV-genomes nor SBV-antibodies could be detected. The 2 semen batches which led to infection of inoculated animals had Cq-values of 26.4 and 34.2, respectively.

Based on those data, it has to be concluded that samples with a medium as well as with a low viral genome load (Cq values over 30) can be potentially infectious for bovines. These results confirm the requirement for a sensitive viral RNA-extraction as well as SBV-genome detection system for testing of semen from SBV-infected bulls.

[Dr Martin Beer and Dr Bernd Hoffmann (Institute of Diagnostic Virology, Friedrich-Loeffler-Institut Insel Riems, Greifswald-Insel Riems, Germany)
Prof Dr Dr Thomas Mettenleiter (President Friedrich-Loeffler-Institut Insel Riems, Greifswald-Insel Riems, Germany)]

--
Dr Martin Beer
Head Institute of Diagnostic Virology
Friedrich-Loeffler-Institut

[The above, firsthand information is gratefully acknowledged. In a previous report from same German authors, they indicated that intermittent SBV excretion was observed in semen of SBV-positive bulls in some of the cases (posting 20121220.1460864). These observations have been confirmed in Dutch and French institutes. They indicate that SBV behaves differently from another Simbu-group teratogenic virus, namely Akabane virus (in Australia).

The current report provides intermediate results of the ongoing research on the issue. The experiment calves were inoculated subcutaneously with the semen. It may be anticipated that the actual potential infectivity of SBV semen will also be tested by insemination.

These essential studies are meant to facilitate the data enabling a science-based decision upon the need for international requirements, including tests, as conditional for trade in semen from SBV-positive/suspected bulls and from SBV-infected zones or countries. - Mod.AS]

[Gert van der Hoek]

Re: Detection of Schmallenberg virus in bull semen

Risk of infection via insemination seems to be very small, but can't be ecxluded?

Published online: 09 October 2013

Schmallenberg virus detection in bovine semen after experimental infection of bulls

SUMMARY

To study Schmallenberg virus (SBV) excretion in bovine semen after experimental infection, two bulls were inoculated subcutaneously with a SBV isolate (1 ml Vero cell culture 106 TCID50).

After inoculation (at day 0), semen was collected daily from both animals for 21 days and samples were tested for SBV by qRT?PCR assay.

At 24 days post-inoculation both animals were subjected to necropsy and the genital organs and lymph nodes draining these organs were also tested for SBV RNA (qRT?PCR).

After SBV infection both animals in the study showed viraemia (qRT?PCR) with fever and diarrhoea. SBV RNA could be detected in semen from both animals. The highest SBV RNA concentrations in semen were found in the first week (days 4?7 post-inoculation) but concentrations were relatively low (Ct values 30?39).

Viable SBV was only isolated from blood samples and not from semen or genital tissues.

http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=9036604